... it's more like an intermittent freeze that lasts <1 sec. ...
It may be an issue with loading data, but switching to SSD probably won't solve it. This is rather a software problem.
Try different v-sync settings in your graphic cards control panel (which graphic card btw and which OS?)
Do you have multiple graphic chips? If so make sure the game doesn't use an embedded chip, but your stronger, dedicated GPU (you can often force it, by assigning it to the game in the graphic card's control panel).
Check if running the game with admin rights makes a difference (right-click the game's shortcut => Run as administrator).
There were also issues with interfering USB devices. Unplug everything you don't need for testing.
Also keep an eye on programs running in the background, close everything for testing, especially anti-virus software (go offline before, if you feel unsafe).